Custom Slicer: Unrelated Fields

I've got a project in which we're trying to do what if calculations based on a number of variables. One of the design requirements is that overall relationship between the whatif parameters, so I'm trying to implement a custom visual to allow for a better UI scheme to alter multiple parameters.

I've got as far as a basic slicer implementation that works for one, but if I try and add multiple Parameter tables to the control I get the error that Power BI "Can't determine relationships between the fields". Technically that's correct, it shouldn't be able to determin a relationship as they aren't related (at least in terms of things I can display in the power BI relations system) Is it possible to override this check and simply accept multiple input items to my slicer that I can apply filters to?

If I can't avoid this validation what else can I do? Can I have multiple visualizations bound together and collaborate on slicing in some way?